3²/2×4+5²/4×6+7²/6×8+9²/8×10+11²/10×12=?简便算法急急急急
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/16 23:28:38
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3²/2×4+5²/4×6+7²/6×8+9²/8×10+11²/10×12=?简便算法急急急急
3²/2×4+5²/4×6+7²/6×8+9²/8×10+11²/10×12=?简便算法
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3²/2×4+5²/4×6+7²/6×8+9²/8×10+11²/10×12=?简便算法急急急急
3²/2×4+5²/4×6+7²/6×8+9²/8×10+11²/10×12
=5+1/2×4+1/4×6+1/6×8+1/8×10+1/10×12
=5+(1/2-1/4+1/4-1/6+1/6-1/8+1/8-1/10+1/10-1/12)÷2
=5+(1/2-1/12)÷2
=5+5/24
=5又5/24
3²/2×4+5²/4×6+7²/6×8+9²/8×10+11²/10×12=(2*4+1)/2×4+(4*6+1)/4×6+(6*8+1)/6×8+(8*10+1)/8×10+(10*12+1)/10×12=5+1/(2*4)+1/(4*6)+1/(6*8)+1/(8*10)+1/(10*12)=1/2*(1/2-1/4+1/4-1/6+1/6-1/8+1/8-1/10+1/10-1/12)=1/2*(1/2-1/12)=5/24